nginx.conf

# /etc/nginx/nginx.conf
http {
    access_log /dev/stdout;
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;
    proxy_cache_path /tmp levels=1:2 keys_zone=thumbs:10m inactive=24h max_size=1G;

    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';

    sendfile        on;
    keepalive_timeout  65;

    client_max_body_size    10m;
    client_body_buffer_size 128k;

    proxy_redirect          off;
    proxy_connect_timeout   30;
    proxy_send_timeout      30;
    proxy_read_timeout      30;
    proxy_buffers           32 4k;
    proxy_buffer_size       8k;
    proxy_set_header        Host $host;
    proxy_set_header        X-Real-IP $http_x_real_ip;
    proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_headers_hash_bucket_size 64;

    include /etc/nginx/conf.d/*.conf;
}

# /etc/nginx/conf.d/rails_app.conf;
upstream rails_app {
    server 127.0.0.1:3003;
}

server {
    listen 8083;

    location ~ ^/(assets)/  {
      gzip_static on;
      expires max;
      add_header Cache-Control public;
      proxy_pass http://rails_app/assets;
      break;
    }

    location / {
      proxy_pass http://rails_app;
    }
}